Abstract: Network access apparatus includes a slave unit, including a plurality of subscriber ports adapted to be linked to respective subscriber lines, and a multiplexer for multiplexing among the ports. A master sub-system, is connected to at least one trunk line of a first public network, in a location remote from the slave unit. The master sub-system includes a first master unit, adapted to communicate with the slave unit via an assigned link through a second public network, so as to provide users of the subscriber lines with access to the first public network through the at least one trunk line. The master sub-system also includes a second master unit, coupled through the first master unit to communicate with the slave unit via the assigned link, so as to provide the users with access to the first public network through the at least one trunk line in the event of a failure associated with the first master unit.